Here in the vast wilderness surrounding Peru's Alto Purús National Park, the locations of such trees, worth tens of thousands of dollars in the United States, have become closely guarded secrets among members of indigenous tribes.

Industrial logging is pushing ever deeper into the area, making mahogany the leading front in the ever-growing battle for control of the resource-rich Peruvian Amazon. But the threat goes far beyond any single species, said Chris Fagan, director of the Upper Amazon Conservancy.

World-renown doctor who owned Lakeland Veterinary Hospital and conducted research on paralyzed swans and dead birds since onset of the Gulf of Mexico operation has disappeared, just before due to release his research. Citizen reporters trying to locate him continue to be stonewalled, even someone who has known him for years who says his sudden absence is out of character.

Seeking to reassure major power plant and factory owners that impending regulation of climate-altering gases will not be too burdensome, the Environmental Protection Agency emphasized on Wednesday that future permitting decisions would take cost and technical feasibility into account.

Under the Obama administration, the E.P.A. declared that gases that contribute to global warming are a danger to human health and the environment and thus must be regulated under the Clean Air Act. The agency is starting with the largest sources of such emissions — coal-burning power plants, cement factories, steel mills and oil refineries — and then will extend the regulations to smaller facilities.

Two months ago, U.S. EPA wrote nine major natural gas drilling companies a letter. It politely asked the recipients to voluntarily tell agency officials the secret brew of chemicals they use to "frack" gas from the shale deposits.

EPA wasn't even planning to make the ingredient list public, a policy the industry is fighting tooth-and-nail in Congress. Instead, it just wanted the information to help with a crucial first-ever federal study of the health and safety risks of hydraulic fracturing, a drilling technique that has already ruined water and air quality in towns across the country and has proceeded unregulated thanks to the Dick Cheney-pushed "Halliburton loophole" passed in 2005.

The illegal trade in tiger parts has led to more than 1,000 wild tigers being killed over the past decade, a report suggests. Traffic International, a wildlife trade monitoring network, found that skins, bones and claws were among the most common items seized by officials.

The trade continues unabated despite efforts to protect the cats, it warns. Over the past century, tiger numbers have fallen from about 100,000 individuals to just an estimated 3,500.

The long list of possible suspects has included pests, viruses, fungi, and also pesticides, particularly so-called neonicotinoids, a class of neurotoxins that kills insects by attacking their nervous systems. For years, their leading manufacturer, Bayer Crop Science, a subsidiary of the German pharmaceutical giant Bayer AG (BAYRY), has tangled with regulators and fended off lawsuits from angry beekeepers who allege that the pesticides have disoriented and ultimately killed their bees. The company has countered that, when used correctly, the pesticides pose little risk.

With Republicans in control of the House of Representatives, powerful Texans such as Rep. Joe L. Barton of the House Energy and Commerce Committee have vowed to check the Environmental Protection Agency's efforts to use its existing authority to curtail greenhouse gases.

An even more ambitious challenge is coming directly from the Texas state government and leading Texas politicians. State Attorney General Greg Abbott, with the support of Republican Gov. Rick Perry, has filed seven lawsuits against the EPA in the last nine months.